tencent cloud

What is HTTPDNS?

HTTPDNS sends DNS requests to the DNS server of Tencent Cloud over the HTTP protocol instead of the local DNS of the ISP over the DNS protocol. This helps avoid domain name hijacking and cross-network access problems caused by local DNS and eliminate DNS exceptions in mobile internet services.

What is the purpose of HTTPDNS?

The purpose of HTTPDNS is to address DNS query exceptions and domain hijacking on the mobile internet:

• Status quo of mobile DNS: the local DNS egress of an ISP performs NAT based on the destination IP address of the authoritative DNS or forwards DNS requests to other DNS servers. This prevents the authoritative DNS from correctly identifying the local DNS IP of the ISP and thus gives rise to DNS query errors and cross-network traffic.
• Consequences of domain hijacking: no network access (inability to connect to the server) or access to a phishing website.
• Consequences of cross-domain, cross-region, cross-ISP, or cross-border DNS queries: slow or even no website access.

How does HTTPDNS work?

• The client directly accesses the HTTPDNS APIs to get the optimal IP of the domain. (For disaster recovery reasons, we recommend you retain your ISP's local DNS as a backup.)
• After the business IP is obtained, the client directly sends requests to it over the business protocol; for example, for HTTP requests, the client can specify the host field in the headers and then send standard HTTP requests to the IP returned by HTTPDNS.

How is the quality of HTTPDNS?

HTTPDNS is highly available and responsive.

• BGP Anycast network deployment: HTTPDNS is connected to the BGP Anycast network architecture to establish BGP interconnection with top 17 Chinese ISPs. This ensures that user requests from ISPs can quickly access the HTTPDNS server. More ISPs are being connected to guarantee a faster service response.
• Remote disaster recovery and real-time failover: HTTPDNS has multiple nodes in multiple IDCs across China. If any node fails, it can seamlessly switch to a backup node to ensure high service availability.

What features does HTTPDNS Enterprise Edition provide?

• Proprietary intelligent SDKs (available for iOS and Android) that cover more than 100 million users.
• Support for encryption.
• SLA of up to 99.99%.
• Unlimited queries.
• Support for user access distribution reports.
• Support for EDNS Client Subnet.
• Ticket and telephone support.

What is the API request rate limit of HTTPDNS?

• For Enterprise Edition users, there is no limit on the API request rate of the client application.
• For free trial users, the request limit is 100 QPS per IP and 1,000 QPS per domain. After the limit is exceeded, packet loss or response failure/delay will occur. We recommend you use Enterprise Edition for your business to avoid being affected by the rate limit. For directions, see Activating HTTPDNS.

Where are HTTPDNS nodes distributed?

HTTPDNS nodes are distributed globally as follows: